Polyzoa of the St. Lawrence. 151 
Eschara palmata of Sars seems to be referable to the same 
form *, 
On a consideration of the whole question I can only suggest 
that probably we have to do with one of the species in which 
the orifice of the cells bearing the ocecium differs in structure 
from that of the ordinary cells. The larger specimens both 
from Barents Sea and the St. Lawrence were thickly covered 
with ocecia, and on these I have been unable to find an 
example of the orifice with the central sinus. On specimens 
of the smaller form from the St. Lawrence the latter was 
universally present. At the same time it must be admitted 
that the exclusive presence of one form of cell throughout 
fine and well-developed colonies affords a presumption against 
the explanation which I suggest. In similar cases the two 
classes of cell are always, so far as I know, mingled together. 
The alternative view would be that these forms are distinct 
species, which seems to be highly improbable. 
Opinions have differed widely as to the precise systematic 
position of Flustra solida, Stimpson, who first described it, ‘ 
referred it to Hlustra, to which it bears a certain amount of 
superficial resemblance ; but there is no real affinity between 
the two. Sars ranked it in the old genus Hschara, simply on 
the ground of its zoarial habit, whilst Verrill placed it in the 
Flustramorpha of Gray, a genus since adopted by Busk for 
forms with a Microporellidan cell and an erect mode of 
growth. Such a genus can of course find no place in our 
later systems of classification T. 
Smitt has discussed the affinities of this species in the light 
of the new views of which he has been so able an expositor, 
and assigns it a place in his genus Hscharella, which (as 
finally limited) is identical with Smettia {. Undoubtedly 
there are points in which it agrees with the members of this 
genus, though the differences are by no means unimportant. 
The orifice in such a species as Smittda reticulata before the 
development of the peristome bears the closest resemblance 
to that of Flustra solida in its larger form, the presence of a 
central denticle and of marginal spines being the only points 
of difference §. But Prof. Smitt had not met with the other 
form of orifice carrying a sinus on the lower margin, which 
* In Stimpson’s figure the avicularium is represented as small and 
suborbicular. 
+ Verrill makes the presence of “chitinous fibres strengthening the 
zoarium ” the distinctive generic character. But this is common to many 
very dissimilar forms. 
{ ‘ British Marine Polyzoa,’ vol. i. p. 541. 
§ ‘History of British Marine Polyzoa,’ pl. xlvili. fig, 4. 
